1. Field of the Invention
The present invention relates to a silicon wafer and a method for testing the same, and more particularly to a silicon wafer having testing pad(s) and a method for testing the same.
2. Description of the Related Art
FIG. 1 shows a cross-sectional view of a first conventional silicon wafer. The silicon wafer 1 comprises a silicon substrate 11, an insulation layer 12, a pad 13 and a dielectric layer 14. The insulation layer 12 is disposed on the silicon substrate 11. The pad 13 is disposed on the insulation layer 12. The dielectric layer 14 is disposed on the insulation layer 12. The dielectric layer 14 covers the pad 13, and exposes a surface 131 of the pad 13.
The conventional silicon wafer 1 has the following disadvantages. Before forming a through via 19 under the pad 13, the silicon substrate 11 must be etched to form a through hole 15. However, during the formation of the through hole 15, the etching rate at the center of the through hole 15 is greater than that at the periphery of the through hole 15, so that the shape of the top of the through hole 15 is similar to arc, and the through hole 15 only exposes a little part of the pad 13. When forming a seed layer 16 on the wall of the through hole 15 in the following processes, even if the pad 13 and the seed layer 16 are already electrically connected to each other, the connecting area between the pad 13 and the seed layer 16 is small, causing higher resistance and bad influence to electrical property.
FIG. 2 shows a cross-sectional view of a second conventional silicon wafer. The silicon wafer 1A is formed by forming a conducting layer 17 on the seed layer 16 of the silicon wafer 1 (FIG. 1) and removing part of the silicon substrate 11, so as to form a plurality of grooves 18. The grooves 18 surround the seed layer 16 and are used to be filled up with an isolating material (not shown), so that the seed layer 16 and the silicon substrate 11 are electrically insulated with each other. Therefore, the grooves 18 must penetrate through the silicon substrate 11, and expose the insulation layer 12. However, conventionally, the silicon wafer 1 must be sliced after the grooves 18 are formed, so as to observe the cross-sectional structure of the grooves 18 in order to know whether the grooves 18 actually penetrate through the silicon substrate 11, which increases manufacturing cost.
Therefore, it is necessary to provide a silicon wafer having testing pad(s) and a method for testing the same to solve the above problems.